The invention relates to two isolation adapters and a method for checking a functionality of a vehicle component during a test drive.
In the development of an electronic controller, such as a controller for an anti-lock brake system or for a tire-pressure monitor for example, provision can be made to check a prototype of the controller during a test drive. In this way, it is possible to determine, for example, how the controller behaves when a sensor from which the signal is required by the controller for operating in the intended manner fails during driving.
For a test drive of this kind, the controller is installed in a car and connected to the actuators and sensors which are to be operated from the controller. Instead of connecting the actuators and sensors directly to the controller in the process, the electrical connection is established via an isolation adapter. In the simplest case, said isolation adapter may be a patchboard to which the controller and the peripheral components (actuators and sensors) are connected. The electrical connections are then established by inserting individual short-circuiting links into a patchpanel of the patchboard. A test driver can then deliberately interrupt individual connections by pulling out short-circuiting links during the test drive. Similarly, it is possible, for example, to create a short circuit in a connecting line by plugging a cable in.
If the test driver then observes undesired reactions of the controller, he can read off the existing connection pattern of the controller to the peripheral components on the patchpanel. However, this is neither detected by measurement nor clearly displayed on a display.
DE 196 16 516 C1 discloses an isolation adapter in which an electrical connection between a unit under test, that is to say a controller for example, and a sensor or actuator can be interrupted by an isolation device being folded out of a corresponding compartment. It is possible to use the folded-out isolation devices to identify which connections are currently interrupted. Short circuits cannot be produced with isolation devices of this kind which can be folded out.
EP 0 678 961 A1 discloses a circuit with which a switching state of a bridge circuit can be electrically detected and displayed by a monitoring circuit. One disadvantage of a circuit of this kind is that a measurement current of the monitoring circuit influences the current flowing in the bridge circuit.
A further disadvantage in modern isolation adapters is that the extent to which the change between two switching states of the isolation adapter itself has an influence on the behavior of the controller is unclear. Therefore, it is possible, for example in the case of a patchboard, for a cable to have an unknown potential during the switchover.
It may also be possible for only a sequence of different faulty connection patterns of a controller which is to be tested to trigger a specific behavior of the controller. This behavior may then be difficult to reproduce.